Tuning unit with trimming condenser



`July 3l, 1951 c. N. EHRLlcH 2,552,263

TUNING UNIT wrm TRIMMING coNDENsEa Filed Aug. 24, "1949 2 Sheets-Sheet 1 July 3l 1951 c. N. EHRLlcH 2,562,263

TUNING UNIT WITH TRIMMING CONDENSER Filed Aug. 24, 1949 2 Sheets-Sheet 2 FIG' .I0

BY MM2,

Vl'atentecl `uly 31,

co-NDENsER Charles N. Ehrlich, New York, N. Y., assignor to Tele-Tone Radio Corporation,` a corporation of New York Application August 24, 1949, Serial No. 112,099

5 Claims. l This invention relates to a condenser mounting and driving mechanism such as used in radio receivers and more particularly to a fine-tuningv or vtrimming condenser associated with a 'channel selector or tuner in television apparatus.

In the past it has been diflicult to design trimming condensers which could be placed in any part of the tuning device. Also it was difficult to reduce stray capacity and to shorten connections while controlling the tuning movement from the front of the receiver panel.

A further diiculty was to assemble the means for channel selection and condenser adjustment in a simple and inexpensive manner yet insuring accuracy of adjustment with least exposure to electric interference.

One of the objects'of this invention is to reduce the coupling mechanism between condenser and panel knobs to a minimum.

A further object of the invention is to arrange tuning and capacity adjustments in such a way as to arrive at a compact piece of equipment which is simple in manufacture and assembly and accurate in operation.

Another object of the invention is a simple `mounting for the condenser, for example a condenser supported on a terminal.

Still another object of the invention is a tuning unit including a trimming condenser which may be easily adapted to and connected With circuits or circuit elements of a high frequency instrument such as a television receiver.

, It is a specific object of the invention to provide v be described more fully in connection with the accompanying drawings of Which:

Figure l represents in perspective a trimming condenser embodying certain features of the in- 'vention.`

Figure 2 represents the condenser in section at an enlarged scale.

Figures 3 and 4 showacondenser mounted toiis-41.5)

nism with the circuit elements of a televisin re- In vFigures 1 and 2, I is a tubing of paper, Bakelite, or other insulating material.

Supported thereon there are two cardboard rings 2 and 3 Which serve to hold metal clips 4 and 5, adapted to support the trimming condenser and also to form electrical connections to its electrodes. These electrodes are constituted by a pair of spaced, ring-shaped ymetal straps 6 and 1.

-Metal straps 6 and 'I are shown to be provided With terminal ends 8, 9 so as to form electrical connections, separate and independent if necessary from the mechanical connections constituted by metal clips 4 and 5.

Inside tubing I there extends a metal cylinder vIUWhich may consist of sheet metal or of metallized paper orplastic. Metal cylinder IIlis `supported on an insulator II, which in turn is held by spring wire I2. Plungerunit Ill, I I, I2 is shown in Figure 2 in a position for capacity at minimum. The position of plunger unit I I), II, I2, for capacity at maximum is shown in dotted lines in Figure 2, at I3.

In Figures 3 and 4 there is shown a channel selector unit 2l, which is attached to chassis 2 2 supporting a bushing 23 vin which the hollow rotatable shaft .24 is mounted. Also mounted on tuning unit 2| there is a trimming condenser 25 consisting of a paper cylinder 26- provided With spaced metal sleeves2'l and 28. The entire condenser 26 is supported on, and connected over end clips 29 and 30, to terminals 3|', 32 of wafers 33, 34 of-tuning unit Ai I.

Condenser 26 may be supported on, -ort-attached to anysorts of terminalssuch as the terminals or a tube socket, without exceeding the scope of the invention, y I

.length of the leads :Sheldto a minimum and stray capacities are practicallyre- .duced to zero. At the same time the condenser adjustment may be effected in accordance with 3 the invention in a very simple way without any undue stress on the condenser mounting.

As illustrated more clearly in Figure 3 there is attached to hollow shaft 24, a cam washer 35 which is fastened to shaft 24 by soldering or any other method of attachment. Cain washer 35 in the course of its rotation and at different points of its periphery, engages cam follower 36, one end of which is att-ached at point 37 to unit 2l. Cam follower 36 is provided with a spring ex'- tension 36' which urges cam follower 36 to continuously contact with cam washer 35.

The other end of cam follower 36 is attached to spring wire 38 which is used for the variation of capacity of condenser 25.

The capacity of condenser 25 is varied by adjustably inserting into paper cylinder 26 a metallic or metallized plunger 39 insulatingly mounted at one end of spring wire 38 the other end of which is attached, as by soldering. at point 4l!V to end 4l of cam follower 36.

Cam follower 36 is shown at an enlarged scale in Figures 5 and 6, cam washer 35 in Figures 7 and 8.

As illustrated more clearly in Figure 9, rotation of k'nob 44 causes rotation of hollow shaft 24 and thereby rotation of cam washer 35 and frictional engagement of cam follower 36 with cam washer 35 at successive peripheral points of the latter. Due to the rotary movement of cam washer 35,l cam follower 36, at a central portion 43 thereof, is elastically pushed backward and forward depending upon the direction of rotation of knob44. Thereby, the adjustable plunger 39 which is insulatingly coupled over wire 3'8" to cam follower 36 is also pushed backward and forward, and thus the capacity of condenser 25 is varied. Hollow shaft 24 contains a second shaft 46 which permits rotary movement of the channel selection unit independent of the tuning adjustment of trimmer condenser 25, all these movements occurring under control of knob from the front of chassis 22. 45 is a housing side plate for chassis 22 for supporting tubes (not shown) on sockets 48. One of these tubes is shown in the circuit diagram of Figure 10 at 49 in which 56 through 56 represent a number of tuning coils mounted on a chassis such as shown in Figures 3 and 4.

Rotation of cam washer 35 and adjustment of condenser 25 are stopped by projection 51 of plate 58 extending through the opening 59 of cam follower 36 in the path of cam washer 35 (Figi. 9');

The trimming condenser 25 is diagrammatically indicated in Fig. 10 at 6D, arranged across inductance 56 the center tap of which is grounded or applied to a :fixed positive .potential of say 1v50`v'olts, over inductance 6I and line 62.

The end terminals of inductance 56 are also connected tothe anodes of twin triode 49 of the 6J6 type.` The anodes of tube 49 as well as its 'grids and its common cathode are connected to ground; the anodes over condensers 63 and 66 of- 4.'7 micromicrofarads and over resistances 64 of 27 kiloohms; the grids over resistances 64 and the common cathode over a common resistance 65 lof 47 ohms.

Structure and arrangement of inductances., condensers and any other circuit elements provided in the unit, and the various mechanical and electrical connections and couplings therebetween, may bel changed or modified inany appropriate mannerv without exceeding the scope of this invention.

, structure and the other end insulatingly coupled to the plunger outside said shell; a portion of said cam follower intermediate its ends being in engagement with said rotary cam so as to impart to said plunger a translatory movement under control of a rotary movement of said cam.

2. In a tuning unit, an operators panel, rotary motion means supported on said panel to be operated from the front of said panel, condenser means supported behind said panel including a cylinder and a plungerI freely movable within said cylinder for capacity adjustment, a flexible cam follower extending substantially radially with respect to the axis of rotary motion, having one end flxedly attached to said panel and another end coupled to said plunger; and a rotary cam supported on said rotary motion means extending both in a direction parallel and perpendicular to the axis of rotary motion and engaging said cam follower at a point intermediate its ends to impart to said plunger a translatory motion substantially parallel but eccentric with respect to the axis of rotary motion.

3. lin a tuning unit, an operators panel, r0- tary motion means supported on said panel to be operated from the front of said panel, condenser means supported behind said panel including a cylinder and a plunger freely movable within said cylinder for capacity adjustment. a wire supporting said plunger at one end thereof. a flexible cam follower extending substantially radially with respect to the axis of rotary motion, having one end xedly attached to said panel and another end coupled t0 the other end of said wire, and a spiral shaped cam washer supported on said rotary motion means and engaging said cam follower at a point intermediate its ends to impart to said wire a translatory motion substantially in the direction of said wire and eccentric with respect to the axis of rotary motion.

4. In a tuning unit, an operator's4 panel, rotary motion means supported on said panell to be operated from the front of said panel, condenser means supported behind said panel including a cylinder of dielectric material having spaced metal layers outside thereof, and a plunger freely movable within said cylinder for capacity adjustment, having a dielectric core, a, metallic layer around said core and a wire supporting said core at one end thereof, a flexible cam follower extending substantially radially with. respect to the axis of rotary motion, having one end xedly `attached to said panel and another end coupled to the other end of said wire; and a rotary cam washer supported by said rotary motion means and engaging said cam follower at a point intermediate its ends to impart to said wire a translatory motion substantially in the direction of said wire.

5. In a tuning unit, an operators panel', a shaft rotably supported thereon, acondenser shell of dielectric material having spaced metal layers outside thereof and terminal clips at its ends supported behind said panel, a plunger movable within said shell for capacity adjustment, having a dielectric core and a metallic layer around said core, a Wire supporting said core at one end thereof, a flexible cam follower extending substantially radially with respect to said shaft, having one end ilxedly attached to said panel and another end coupled to the other end of said wire; and a rotary cam Washer supported on said shaft and engaging said cam follower at a point intermediate its ends so that when shaft and Washer are rotated said follower will impart to said Wire a motion substantially in the direc- 15 tion of said wire.

CHARLES N. EHRLICI-I.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 286,215 Mills Oct. 9, 1883 1,632,649 Hartman June 14, 1927 1,633,870 Potter June 28, 1927 10 2,433,105 Renniek sept. 27, 1949 FOREIGN PATENTS Number Country Date 541,712 Great Britain Dec. 8, 1941 

